Seems to come from the Penguin version (QV).

See how my love do tumble,
See how my love do taver,
See how my love do try to swim,
That makes my heart quaver.

The version I sing has

Can't you see how she swims, my boys,
Can't you see how her body quivers,
She'll swim till she comes to
The Banks of Green Willow.

Could be an indication.

:-)